Safety device for protecting an operator{40 s hands

ABSTRACT

A safety device for protecting an operator&#39;&#39;s hands from the cutting edge of the blade of a band saw characterized by a shield disposed in a protective relationship with the blade and supported for rectilinear reciprocation along a path paralleling the plane of the blade, a double-acting pneumatic cylinder for imparting rectilinear motion to the shield, and a feeler disposed in juxtaposition with the shield and connected therewith for initiating operation of the cylinder in response to an engagement therewith of a selected workpiece as the workpiece is advanced toward the blade.

United States Patent 1 91 1111 3,848,502 ONeill 1451 Nov. 19, 1974 [54]SAFETY DEVICE FOR PROTECTING AN 3,648,552 3/1972 Bradley 83/544 XOPERATOR 'S HANDS Edwin R. ONeill, 2393 Barstow Ave., Fresno, Calif.93705 Filed: Nov. 5, 1973 Appl. No.: 413,356

Inventor:

U.S. Cl 83/814, 83/544, 83/440.2, 83/860 Int. Cl B26d 4/22, 326d 7/22Field of Search 83/814, 860, 544, 446, 83/422, 440.2

References Cited UNITED STATES PATENTS 3/1921 McDonnell 83/814 10/1955Dremel 9/1963 Bretthauer 83/814 Primary Examiner-Willie G. AbercrombieAttorney, Agent, or Firm-Huebner & Worrel [57] ABSTRACT A safety devicefor protecting an operators hands from the cutting edge of the blade ofa band saw characterized by a shield disposed in a protectiverelationship with the blade and supported for rectilinear reciprocationalong a path paralleling the plane of the blade, a double-actingpneumatic cylinder for imparting rectilinear motion to the shield, and afeeler disposed in juxtaposition with the shield and connected therewithfor initiating operation of the cylinder in response to an engagementtherewith of a selected workpiece as the workpiece is advanced towardthe blade.

7 Claims, 7 Drawing Figures SAFETY DEVICE FOR PROTECTING AN OPERATOR'SHANDS BACKGROUND OF THE INVENTION The invention relates to safetydevices for protecting an operators hands from the cutting edge ofblades disposed in a vertically oriented plane and more particularly toa safety device for protecting the hands of a meat cutter as he employsa band saw in the performance of meat cutting operations.

As can readily be appreciated by those familiar with the art of cuttingmeat, large and heavy cuts of meat often are sent through a band saw forpurposes of reducing their bulk and weight prior to being supplied to anultimate consumer. Such cuts, of course, frequently lack uniformity, arechilled, and are quite heavy and are difficult to handle. Moreover, thecuts frequently are coated with layers of fatty tissues. This, coupledwith the additional fact that meat cutting procedures normally must beperformed by highly paid personnel, tends to increase production costs.As a natural consequence, personnel involved in meat cutting operationsattempt to feed band saws employed in cutting meats at rapid rates.This, in turn, tends to lead to injuries being suffered by suchpersonnel.

To date, band saws employed in meat cutting operations simply have notbeen provided with suitable safety devices capable of protecting anoperators hands. It is therefore the general purpose of the instantinvention to overcome the aforementioned difficulties by providing asafety device, including a shield for the blade of the band saw and afeeler responsive to an engagement therewith of a selected cut of meat,for initiating a raising and lowering of the shield through a throwequal to the vertical thickness of the cut of meat.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of theinstant invention to provide an improved safety device for band saws.

It is another object to provide a safety device for protecting anoperators hands as he employs a band saw in performing meat cuttingoperations.

It is another object to provide a safety device for use with band sawsincluding a shield disposed in a protective relationship with the bladeof a band saw and a feeler supported in juxtaposition with the shieldfor detecting a workpiece as the workpiece is advanced toward the bladeand an actuator responsive to a detection of the workpiece for elevatingthe shield through a throw equal to the vertical thickness of theworkpiece.

These and other objects and advantages are achieved through the use ofan elongated shield circumscribing a vertical segment of a run for aband saw blade and supported for rectilinear motion along a pathparalleling the segment, a cyclically operable fluid-driven actuatorhaving a linear output shaft for imparting rectilinear motion to theshield, a flow control valve and a feeler connected therewith andsupported in juxtaposition with the shield for initiating operation ofthe actuator in response to an engagement therewith of a cut of meat asthe cut is advanced toward the blade, as will hereinafter become morereadily apparent by reference to the following description and claims inlight of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation of a bandsaw equipped with a safety device embodying the principles of theinstant invention. 1

FIG. 2 is an end view of the band saw shown in FIG.

FIG. 3 is a sectional view taken generally along line 3-3 of FIG. 2.

FIG. 4 is a fragmentary view on an enlarged scale illustrating anoperative relationship of the safety device with the blade of the bandsaw shown in FIG. 2.

FIG. 5 is a fragmented view of a selector valve employed in controllingthe safety device of the instant invention.

FIG. 6 is a cross-sectional view, taken generally along line 6-6 of FIG.5.

FIG. 7 is a schematic view of a control system employed for controllingthe operation of the safety device of the instant invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now with morespecificity to the drawings, wherein like reference characters designatelike or corresponding parts throughout the several views, there is shownin FIG. 1 a band saw, generally designated 10, embodying the principlesof the instant invention.

It should here be noted that the band saw 10 is a commercially availabledesign and is of a type frequently found in butcher shops, meat packingplants and the like. Since such saws are well known, a detaileddescription of the saw 10 is omitted in the interest of brevity.However, it is to be understood that the band saw 10, as illustrated,includes a blade 12 and has particular utility in cutting large cuts ofmeat 14 preparatory to their being supplied to consumers, retailers andthe like. The blade 12 is supported by a pair of vertically spaced,coplanar drums driven along a unidirectional path including a pair ofmutually spaced, vertically oriented runs extending between the drums. Atable 16 is provided for supporting the cuts of meat 14 as they are fedto the blade 12 by an operator, such as a meat cutter.

As illustrated in the drawings, the band saw 10 is provided with asafety device, generally designated 20, which embodies the principles ofthe instant invention. The safety device 20 includes a verticallyoriented shield 22, formed of a right-angle extrusion, which partiallyencases the blade 12 in a protective disposition relative to the bladescutting edge or teeth.

While not shown, it is to be understood that the shield 22 is supportedat its uppermost end by suitable bearing structures, which accommodatevertical reciprocation. At its lowermost end, the shield 22 is supportedby a lifting plate 24 connected therewith in any suitable manner. Theplate 24, in turn, is united with a vertically oriented guide rod 26,also in any suitable manner, as by welding and the like. The guide rod20.

nated 30. The cylinder 30 includes a barrel suspended to the housing ofthe band saw blade 10, in an inverted disposition, by a suitable cleviscoupling 31. The cylinder 30 also includes a downwardly extended pistonshaft 32, which serves as an output shaft supported for rectilinearreciprocation. Reciprocation is imparted to the shaft 32 as the endportions of the barrel are reversely pressurized, in a manner and for apurpose well understood by those familiar with double-acting, pneumaticcylinders.

At the distal end of the output shaft 32, there is a clevis 34. Theclevis 34 is pinned to a bracket 36 by a suitable pin 38, which, inturn, is affixed to the guide rod 26 at its lowermost end. Thus theshaft 32 is connected with the shield 22 through the plate 24 and thebracket 36.

Therefore, it should be apparent that as the output shaft 32 isretracted, relative to the barrel of the double-acting pneumaticcylinder 30, the guide rod 26 and the shield 22 simultaneously areelevated through a distance dictated by the length of the stroke orthrow of the output shaft. Similarly, the shield 22, along with theguide rod 26, are lowered through a distance dictated by the throw ofthe shaft 32, as the shaft is extended relative to the barrel of thecylinder 30.

It is to be clearly understood that the shield 22 normally is disposedin protective relation with the blade 12. However, upon a retraction ofthe output shaft 32, relative to the barrel of the cylinder 30, theshield 22 is elevated out of such relation with the blade 12. Thus afeeding of a cut of meat 14 to the blade 12 is facilitated. Oncelowered, the shield 22 serves to protect the hands of the operator fromthe effects of the blade.

Pressurization of the barrel of the cylinder 30, for advancing the shaft32 in extension and retraction strokes, is dictated by a selector valve40. This valve communicates with the end portions of the barrel of thecylinder 30 through a pair of pressure lines 42 and 44, coupled withsuitable ports provided within the opposite end portions of the barrelof the cylinder 30. The selector valve 40 also is connected, through apressure line 45, with a pump or other suitable source of pressurizedfluid, designated 46, FIG. 7.

While a liquid hydraulic fluid could be employed equally as well forpurposes of pressurizing the cylinder 30, pneumatic fluid is preferredin order to achieve a more rapid response. Of course, therate of theresponse achieved must be consistent with the intended mode of operationfor the device 20. Consequently, in order to control the rate at whichthe shield 22 is elevated and lowered, a flow restrictor 48 is connectedin each of the pressure lines 42 and 44, immediately adjacent the barrelof the cylinder. Thus by varying the rate of flow of fluid through therestrictors 48, the rate at which the shaft 32 is advanced is preciselycontrolled for thereby accurately controlling the rate at which theshield 22 is raised and lowered.

As shown, the valve 40 is a three-position valve and includes a housing50 and a spool 52 supported for rotation within the housing.Additionally the housing is provided with a first pressure port 54, asecond pressure port 56 and an exhaust port 58. Within the spool 52there is formed an axial bore 60. This bore is connected with the sourceof fluid 46 through a suitable port, not designated, and the pressureline 45. The spool 52 also includes, in communication with the bore 60,a first radial bore 62 and a second radial bore 64 axially spaced fromand angularly related to the first radial bore 62. These radial boresare alternatively aligned with the pressure ports 54 and 56, when thespool 52 is advanced to positions at the extremities of its throw.

About the spool 52 there is provided an arcuate groove 66 of an angularlength such that one pressure port 54 or 56 can be caused to communicatewith the exhaust port 58, via the arcuate groove, while the otherpressure port is in communication with the axial bore 60, via one of theradial bores 62 or 64. Hence, it is to be understood that when either ofthe ports 54 or 56 is in communication with the axial bore 60, via oneof the radial bores 62 or 64, the exhaust port 58 is in directcommunication with the double-acting pneumatic cylinder 30. Moreover,the groove 66 and the radial bores 62 and 64 are so interrelated thatthe spool 52 can be rotated to a centered position wherein neither ofthe pressure lines 42 or 44 is in communication with either the axialbore 60 or the exhaust port 58. Thus, it is possible to arrestpressurization of the cylinder 30 and hence the motion of the outputshaft 32.

The spool 52 further includes an axially extended stub shaft 67. Thisshaft is extended from the housing 50 and receives an actuator arm 68.The arm 68 is secured to the stub shaft 67 through any suitable meansincluding a pin 70. Preferably, the arm 68 includes a base segment 72,FIG. 5, radially extended from the stub shaft 57 and an angularlyrelated distal segment 74. This segment, in practice, is arranged insubstantial parallelism with the axis of rotation for the spool 52.Consequently, oscillatory motion is imparted to the spool 52 as thedistal segment 74 of the arm 68 is caused to oscillate about the valve40. Thus, the valve 40 is manipulated.

The arm 68 is spring-biased in a first direction by a suitablecompression spring 76, FIG. 4, suitably seated on the valves housing, inan abutting engagement with the arm 68. Displacement of the arm 78 in asecond direction, opposite to the first direction, is achieved through ause of an actuator arm 78 rigidly affixed to and extended from a skid,generally designated 80 which functions as a feeler for sensing thepressure of a cut of meat.

The skid 80 is coupled with the bracket 36 through ajournal 82 andincludes a base 84 to which the journal 82 is connected. The arm 78 alsois affixed, as by welding and the like, to the base 84. Extendedforwardly from the base 84, at opposite sides of the blade 12, is abifurcated framework 86 having an upturned distal portion 88 whichimparts an inclined configuration to the skid 80. An arcuate connectingmember 90 extends between the opposite sides of the bifurcated framework86. The skid 80 is caused to pivot about the journal 82, as the forwardend thereof is lifted, whereupon the distal end of the extended arm78 iscaused to engage the arm 68. Continued pivotal motion of the skid servesto impart additional angular displacement to the arm 78, whereuponthe'arm 68 is caused to impart angular displacement to the spool 52within the housing 50 of the valve 40.

As a practical matter, the connection between the distal end of the arms68 and 78 is accommodated through a pad 92 affixed to the distal segment74 of the arm 68 and a protuberance 94 adjustably secured to the distalend of the actuator arm 78. The protuberance 94, as shown, is anelongated screw-threaded member received within a screw-threadedopening, not designated, provided in the distal end of the actuator arm78. By advancing or retracting the protuberance 94, relative to theplanes of the arm, the effective angular relation of the skid 80 to thespool 52 can be varied. Thus the spool 52 is caused to rotate through apredetermined angle, relative to the ports 54, 56, and 58, as the skid80 is pivotally displaced through a predetermined angle relative to ahorizontal plane. It will therefore be appreciated that the shield 22 iselevated through a throw dictated by the angular displacement of theskid 80 as a cut of meat is caused to engage the distal end 88 androtate the skid about the journal 82. Of course, the shield issubsequently lowered in response to a disengagement of the cut of meatwith the skid.

Moreover, since the cylinder 30 is a double-acting pneumatic cylinder,controlled by the position assumed by spool 52, the bracket 36 iselevated, as the spool is advanced to a first position, through adistance sufficient only for accommodating a passage of a cut of meatbeneath the skid, due to the fact that as the skid 80 is caused toachieve the horizontal disposition a responsive centering of the spool52 occurs. Once the skid 80 is permitted to rotate, in an oppositedirection, the spool 52 also is caused to be rotated in an oppositedirection to a second position under the influence of the spring 78 forthereby oppositely pressurizing the cylinder 30. Such pressurization ofthe cylinder 30 causes the bracket 36, and hence the shield 22, to belowered until such time as the skid 80 engages the surface of the table16 for thus causing the spool 52 to center. Thus motion of the shield isarrested.

OPERATION It is believed that in view of the foregoing description, theoperation of the device will readily be understood and it will bebriefly reviewed at this point.

With the safety device 20 mounted on the band saw 10, in the mannerhereinbefore described, the device is prepared for use in performingmeat cutting operations.

An operator grasps a cut of meat 14 and forces it beneath the distal endportion 88 of the skid 80 whereupon the skid 80 is caused to pivot atits journal 82 for initiating a cycle of operation. Pivotal motion ofthe skid 80 causes the distal end of the threaded protuberance 94 toengage the pad 92, located at the distal end of the arm 68. As the cutof meat is advanced beneath the skid 80, the skid is caused to continueto rotate. Such continued rotation of the skid causes angulardisplacement to be imparted to the spool 52, within the housing 50 ofthe selector valve 40. Sufficient rotation of the spool 52 causes thespool to be advanced to its first position wherein the radial bore 64 isbrought into alignment with the pressure port 56. At this instant, thesource of pneumatic pressure 46 is caused to communicate with thecylinder 30, via the bores 60 and 64, within the spool 52, the pressureport 56 and the pressure line 42. Hence, the output shaft 32 isretracted relative to the barrel of the cylinder as pressure isintroduced into the lowermost end of the cylinder 30. Retraction of theshaft is accommodated as the uppermost end of the cylinder 30 ispermitted to communicate with the exhaust port 58, via the pressure line44, the pressure port 54 and the arcuate groove 66. However, due to theeffects of the flow restrictors 48, within the pressure lines 42 and 44,the rate at which retraction of the output shaft 32 is retarded.

As the shaft 32 is retracted, the lifting plate 24 is elevated forthereby lifting the shield 22 for accommodating the passage of the cutof meat through blade 12. Of course, once the lifting plate 24, as wellas the bracket 36, has been lifted a distance sufficient foraccommodating a passage of the cut of meat 14, beneath the skid 80, theskid assumes a zero angular relation with respect to the horizontal,whereupon the spool 52 is rotated to its centered position, under theinfluence of the spring 76. Centering of the spool 52 within the housing50 of the selector valve 40 interrupts communication through the valvewhereupon all motion of the output shaft 32 is arrested.

As the cut of meat 14 is passed beneath the skid 80, the distal end 88is permitted to pivot downwardly, for permitting the arm 68 to befurther displaced, under the influence of the spring 76, whereuponcommunication between the axial bore 60 and the pressure port 54 isestablished through the radial bore 62. Simultaneously therewith, thearcuate groove 66 permits the pressure port 56 to communicate with theexhaust port 58. In this configuration, the selector valve 40 causes thelower end of the double-acting pneumatic cylinder 30 to communicate withambient atmosphere while the upper end of the cylinder is caused tocommunicate with the source of pressure 46 for forcing the output shaft32 in an extension stroke.

Extension of the shaft 32 causes the bracket 36, and consequently thelifting plate 24, to be lowered sufficiently for permitting the skid torest upon the top surface of the table 16. As the skid 80 comes to restit is rotated in an opposite direction for again centering the spool 52within the housing 50 whereupon downward motion of the output shaft 32and the shield 22 is arrested. Thus, a cycle of operation for the safetydevice 20 is completed.

In view of the foregoing, it should readily be apparent that the deviceof the instant invention provides a practical solution to the perplexingproblem of protecting the hands of meat cutters when employing band sawsfor cutting large and unwieldy cuts of meat.

Although the invention has been herein shown and described in what isconceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within the scope of theinvention, which is not to be limited to the illustrative detailsdisclosed.

Having described my invention what I claim as new and desire to secureby Letters Patent is:

1. A safety device for protecting an operators hands from the cuttingedge of a blade disposed in a vertically oriented plate, comprising:

A. a shield disposed in protective relation with a vertically disposedblade supported for linear motion along a vertical path paralleling theplane of the blade; and

B. actuating means responsive to an engagement of a workpiece therewithfor elevating the shield out of protective relation with the blade andfurther responsive to a disengagement of the workpiece for lowering saidshield into protective relation with the blade, including,

1. a fluid driven actuator having an output shaft supported for cyclicrectilinear motion connected with the shield for imparting theretorectilinear reciprocation,

2. means including a cylically operable fluid selector valve responsiveto manipulation for imparting cyclic rectilinear motion to the shaft,and

3. feeler means mounted in juxtaposition with said shield formanipulating said valve in response to sequential engagement anddisengagement with said workpiece.

2. The device of claim 1 wherein said actuating means includes means forlimiting vertical motion imparted to said shield, as the shield iselevated, to a throw equal to the vertical thickness of said workpiece.

3. The device of claim 1 wherein said feeler means includes:

A. a pivotal skid extended in a substantially horizontal directionforwardly of said blade; and B. means including an arm rigidly fixed tosaid skid for manipulating the selector valve.

4. The device of claim 3 wherein said fluid-driven actuator comprises adouble-acting pneumatic cylinder including means defining a pressureport located at each of its opposite ends, and a flow reduction valveconnected with each of the pressure ports for reducing the rate ofrectilinear motion imparted to the shaft.

5. The device of claim 4 wherein said fluid selector valve comprises athree-position valve including a third position wherein said valveinterrupts the flow of pneumatic fluid to either port of saiddouble-acting pneumatic cylinder; a second position wherein pneumaticfluid is directed to a first port; and a first position wherein saidfluid is directed to the other port.

6. A safety device for protecting an operators hands in combination withan endless blade of a band saw having a vertical run and driven inunidirectional displacement, said device comprising:

A. an elongated shield partially circumscribing a segment of the run forsaid blade and supported for rectilinear motion along a path parallelingsaid segment;

B. A cyclically operable, fluid-driven actuator having a linear outputshaft for imparting rectilinear motion to said shield; and

C. means including a feeler disposed in juxaposition with said shieldand connected therewith for initiating operation of said actuator inresponse to an engagement therewith of a selected workpiece as theworkpiece is moved relative to the blade.

7. In a safety device for protecting an operators hands from the cuttingsurface of a device adapted to cut hand-fed workpieces, the improvementcomprising:

A. a shield adapted to be arranged in juxtaposition with a cuttingsurface of a selected device supported for rectilinear motion along asubstantially linear path extending between a first position wherein theshield is disposed in a protective relation with said cutting surfaceand a second position, spaced from said first position, wherein saidshield is disposed in non-protective relation with said cutting surface;and

B. actuating means including a fluid-pressurizable actuator connected tosaid shield adapted to respond to pressurization for moving said shieldfrom said first position to said second position, means for selectivelypressuring said actuator including a selectively operable fluid controlvalve connected to a source of fluid maintained under pressure, andfeeler means connected to said fluid control valve adapted to respond toan engagement with a workpiece for operating the fluid control valve andso disposed as to be engaged by a workpiece as the workpiece is hand-fedto said device.

UNITED STATES' PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 848SQZ Dated N y fi 12 Inventor(s) Edwin R. O'Neill I It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column '7', line 3, delete "cylically" and :i. nsert ---cyc1i .ca11y---.

Signed and sealed this 14th day of January 1975.

(SEAL) Attest: I

OY M. GIBSON JR. c; MARSHALL mm figuring Officer Commissioner of PatentsUSCOMMDC 60376-P69 US. GOVERNMENT PRINTING OFI'ICE 869- 930 F ORMPO-IOSO (10-69)

1. A safety device for protecting an operator''s hands from the cuttingedge of a blade disposed in a vertically oriented plate, comprising: A.a shield disposed in protective relation with a vertically disposedblade supported for linear motion along a vertical path paralleling theplane of the blade; and B. actuating means responsive to an engagementof a workpiece therewith for elevating the shield out of protectiverelation with the blade and further responsive to a disengagement of theworkpiece for lowering said shield into protective relation with theblade, including,
 1. a fluid driven actuator having an output shaftsupported for cyclic rectilinear motion connected with the shield forimparting thereto rectilinear reciprocation,
 2. means including acylically operable fluid selector valve responsive to manipulation forimparting cyclic rectilinear motion to the shaft, and
 3. feeler meansmounted in juxtaposition with said shield for manipulating said valve inresponse to sequential engagement and disengagement with saidworkpiece.
 1. A safety device for protecting an operator''s hands fromthe cutting edge of a blade disposed in a vertically oriented plate,comprising: A. a shield disposed in protective relation with avertically disposed blade supported for linear motion along a verticalpath paralleling the plane of the blade; and B. actuating meansresponsive to an engagement of a workpiece therewith for elevating theshield out of protective relation with the blade and further responsiveto a disengagement of the workpiece for lowering said shield intoprotective relation with the blade, including,
 1. a fluid drivenactuator having an output shaft supported for cyclic rectilinear motionconnected with the shield for imparting thereto rectilinearreciprocation,
 2. means including a cylically operable fluid selectorvalve responsive to manipulation for imparting cyclic rectilinear motionto the shaft, and
 2. The device of claim 1 wherein said actuating meansincludes means for limiting vertical motion imparted to said shield, asthe shield is elevated, to a throw equal to the vertical thickness ofsaid workpiece.
 3. The device of claim 1 wherein said feeler meansincludes: A. a pivotal skid extended in a substantially horizontaldirection forwardly of said blade; and B. means including an arm rigidlyfixed to said skid for manipulating the selector valve.
 3. feeler meansmounted in juxtaposition with said shield for manipulating said valve inresponse to sequential engagement and disengagement with said workpiece.4. The device of claim 3 wherein said fluid-driven actuator comprises adouble-acting pneumatic cylinder including means defining a pressureport located at each of its opposite ends, and a flow reduction valveconnected with each of the pressure ports for reducing the rate ofrectilinear motion imparted to the shaft.
 5. The device of claim 4wherein said fluid selector valve comprises a three-position valveincluding a third position wherein said valve interrupts the flow ofpneumatic fluid to either port of said double-acting pneumatic cylinder;a second position wherein pneumatic fluid is directed to a first port;and a first position wherein said fluid is directed to the other port.6. A safety device for protecting an operator''s hands in combinationwith an endless blade of a band saw having a vertical run and driven inunidirectional displacement, said device comprising: A. an elongatedshield partially circumscribing a segment of the run for said blade andsupported for rectilinear motion along a path paralleling said segment;B. A cyclically operable, fluid-driven actuator having a linear outputshaft for imparting rectilinear motion to said shield; and C. meansincluding a feeler disposed in juxaposition with said shield andconnected therewith for initiating operation of said actuator inresponse to an engagement therewith of a selected workpiece as theworkpiece is moved relative to the blade.